Swing door operator

ABSTRACT

A door operator for a door movable between open and closed positions. The operator includes an endless loop member supported for reversible orbital motion by a pair of spaced rotatable members. A linkage couples one rotatable member to the door. A pressure fluid cylinder has a piston rod connected to one reach of the endless loop member and is actuable in one direction for moving the endless loop member to open the door. Resilient tension return means are coupled to the other reach of the endless loop member and are responsive to cessation of actuation of the pressure fluid cylinder for causing the endless loop member to close the door. The pressure fluid cylinder includes means for decelerating door motion as the door approaches its open and closed positions, including enlarged cam portions on the piston rod thereof cooperating with valved pressure fluid inlet and outlet openings. A control circuit having a variable time delay responds to actuation of actuation and safety switches, by persons using the door, for controlling pressure fluid flow to the cylinder. By appropriate installation, the operator is usable with either right- or left-hand hinged doors and doors which open either inwardly or outwardly. A modified operator substitutes a direct drive connection for the linkage. Other modified operators are usable with sliding doors and with double swinging doors.

United States Patent [191 Hewitt [4 1 Feb. 11, 1975 SWING DOOR OPERATOR[75] Inventor: Lew V. Hewitt, Corpus Christi, Tex.

[73] Assignee: Overhead Door Corporation, Dallas,

Tex.

[22] Filed: Apr. 16, I973 [21] Appl. No.: 351,460

Primary E.\'aminer.l. Karl Bell Attorney, Agent, or Firm-Woodhams,Blanchard & Flynn [57] ABSTRACT A door operator for a door movablebetween open and closed positions. The operator includes an endless loopmember supported for reversible orbital motion by a pair of spacedrotatable members. A linkage couples one rotatable member to the door. Apressure fluid cylinder has a piston rod connected to one reach of theendless loop member and is actuable in one direction for moving theendless loop member to open the door. Resilient tension return means arecoupled to the other reach of the endless loop member and are responsiveto cessation of actuation of the pressure fluid cylinder for causing theendless loop member to close the door. The pressure fluid cylinderincludes means for decelerating door motion as the door approaches itsopen and closed positions, including enlarged cam portions on the pistonrod thereof cooperating with valved pressure fluid inlet and outletopenings. A control circuit having a variable time delay responds toactuation of actuation and safety switches, by persons using the door,for controlling pressure fluid flow to the cylinder. By appropriateinstallation, the operator is usable with either rightor left-handhinged doors and doors which open either inwardly or outwardly. Amodified operator substitutes a direct drive connection for the linkage.Other modified operators are usable with sliding doors and with doubleswinging doors.

26 Claims, 15 Drawing Figures SHEET E OF 7 SWING DOOR OPERATOR FIELD OFTHE INVENTION This invention relates to a door operator and moreparticularly relates to a door operator for switch controlled openingand closing of a door, particularly a swinging door.

BACKGROUND OF THE INVENTION The door operator embodying the presentinvention was developed to fulfill long felt needs in apparatus of thistype. More particularly, although mat actuated power operated doors havelong been known and a wide variety of door and operator systems has beenproposed in the past, same have not proven entirely satisfactory for avariety of reasons. Many prior door operators have been of highmechanical complexity, resulting in high manufacturing and maintenancecosts and unreliability in long-term use. Many prior door operators havenot been versatile in application, being limited to use with aparticular kind of door, e.g. swinging, sliding, etc. Swinging dooroperators have in the past further frequently been incapable of use withboth leftwardly and rightwardly hinged doors or both inwardly andoutwardly swinging doors or have required substantial modification orreplacement of parts to accomplish a change-over from one type ofswinging door to another, requiring large and costly inventories ofdisparate door operator models and replacement parts for each.

Accordingly, the objects of this invention include provision of:

l. A door operator of a simplified mechanical construction havingrelatively few parts and capable of use with little or no replacement ofparts on a wide variety of door types.

2. A door operator, as aforesaid, usable with swinging doors, includingbi-fold doors, and sliding doors as well.

3. A door operator, as aforesaid, usable with either right-handed orleft-handed swinging doors without replacement of parts, simply byreorienting the door operator unit as a whole and repositioning thelinkage by which it connects to the door.

4. A door operator, as aforesaid, usable with either inwardly oroutwardly opening doors, by a minor rearrangement of parts therewithand, in some instances, by use of differing linkage lengths connected tothe differing door types.

5. A door operator, as aforesaid, capable of use with either single ortandem doors and which is'capable of maintaining synchronism of dooropening in tandem door installations.

6. A door operator, as aforesaid, capable of connection to doors inseveral ways, e.g., through a linkage or directly through a rotatingdrive element.

7. A door operator, as aforesaid, which provides for deceleration ofdoor movement to a fully opened or fully closed position, in a smoothand accurately controllable manner.

8. A door operator, as aforesaid, providing for reliable closing of thedoor automatically and despite power failures and the like, and also incase of fire and other specified events, so as to be usable as anautomatically closing fire door.

9. A door operator, as aforesaid. which automatically prevents openingof a swinging door into a person or the like standing in the paththereof.

apparent to persons acquainted with apparatus of this.

general type upon reading the following specification and inspecting theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a partially brokenelevational view ofa door operator embodying the invention, mounted inoperative relation with a left-hand hinged, inwardly swinging door.

FIG. 2 is an enlarged sectional view substantially taken on the lineIl--II of FIG. 1.

FIG. Sis a fragmentary sectional view substantially taken on the lineIII-III of FIG. 2.

FIG. 4 is a diagrammatic central cross-sectional view of the pressurefluid cylinder of FIG. 2, with associated valving, with the piston rodshown in the door-closed position.

FIG. 5 is a view similar to FIG. 4 but showing an intermediate positionof the piston rod during door opening movement.

FIG. 6 is as view similar to FIG. 4 but showing the piston rodpositioned as the door approaches its fully open position.

FIG. 7 is a schematic diagram of electrical circuitry which comprises aportion of the operator of FIG. 2.

FIG. 8 is a view similar to FIG. 2 but showing the door operatorreoriented for use with a right-hand hinged door.

FIG. 9 is a view similar to FIG. 2 but showing the operator arranged foruse with an outwardly swinging door.

FIG. 10 is a view similar to FIG. 2 but showing a modified operatorpositioned directly above the door and arranged for direct drive openingthereof.

FIG. 11 is an elevational view disclosing a modification wherein thedoor is a sliding rather than swinging door.

FIG. 12 is a fragmentary elevational view of a door operator modifiedfor synchronized opening of a pair of swinging doors.

FIG. 13 is a top elevational view of the apparatus of FIG. 12 andutilizing the operator of FIG. 2 as a portion thereof.

FIG. 14 shows a modification of the FIG. 4 apparatus.

FIG. 15 is a modified fragment of FIG. 7 related to FIG. 14.

SUMMARY OF THE INVENTION The objects and purposes of the invention aremet by providing a door operator for a door movable between open andclosed positions. The operator includes an endless loop member supportedfor reversible orbital motion by a pair of spaced rotatable members. Alinkage couples one rotatable member to the door. A pressure fluidcylinder has a piston rod connected to one reach of the endless loopmember and is actuable in one direction for moving the endless loopmember to open the door. Resilient tension return means are coupled tothe other reach of the endless loop member and are responsive tocessation of actuation of the pressure fluid cylinder for causing theendless loop member to close the door. The pressure fluid cylinderincludes means for decelerating door motion as the door approaches itsopen and closed positions, including enlarged cam portions on the pistonrod thereof cooperating with valved pressure fluid inlet and outletopenings. A control circuit having a variable time delay responds toactuation of actuation and safety switches, by persons using the door,for controlling pressure fluid flow to the cylinder. By appropriateinstallation, the operator is usable with either rightor left-handhinged doors and doors which open either inwardly or outwardly. Amodified operator substitutes a direct drive connection for the linkage.Other modified operators are usable with sliding doors and with doubleswinging doors.

DETAILED DESCRIPTION FIG. 1 discloses the interior face of a buildingwall 11 provided with a portal 12 defined in part by spaced, upstandingstiles 13 and 14. The portal is occupied by an inwardly swinging door 16pivotally supported by hinges 17 and 18 on the leftward stile 13.

A door operator 20 is fixed on the interior face of the wall 11 abovethe door 16 for opening and closing said door, as hereinafter discussed.

The operator 20 (FIGS. 2 and 3) includes a housing 22, of horizontallyelongate and generally rectangular form, comprising a back wall 24,front wall 25, end walls 26 and 27, a top wall 28 and bottom wall 29. Inthe particular embodiment shown, the back wall 24 is preferably securedto the stiles 13 and 14 by any conventional means, such as screws notshown. At least a portion of the housing 22, preferably including thefront wall 25, is removable for access to the contents of the housing.

The door operator 20 further includes within the housing 22 a pressurefluid motor unit 31 with associated valving 33, a variable time delaycontrol 34 for controlling such motor unit 31, resilient return means 36and an endless loop unit 38, responsive to the motor unit 31 and returnmeans 36, for opening and closing the door 16.

The motor unit 31 (FIGS. 2 and 3) comprises a pressure fluid (here air)cylinder 41 having end walls 43 and 44, respectively provided withbosses 46 and 47 extending coaxially therefrom. Angle brackets 51 and 52are fixed to the cylinder end 43 and have horizontally extended portionspivotally secured to the top and bottom housing wall 28 and 29, as bycoaxial bolts 54, so as to cantilever the pressure fluid cylinder withinthe housing 22 for horizontal pivoting thereof. An elongate piston rod56 extends from within the pressure fluid cylinder 41 coaxiallyoutwardly through the wall 44 and boss 47.

The return means 36 comprises a reversible bracket 61 of generallyU-shaped configuration, having upper and lower legs 62 removablyaffixed, by any convenient means such as screws 63, to the top andbottom walls 28 and 29 of the housing. An upstanding bight portion 65,preferably integrally extends between corresponding ends of the legs 62and is near an intermediate portion of the cylinder 41. Resilienttension means, here comprising a pair of substantially horizontallyextending, coiled tension springs 66 and 67, are fixed at one end to thebracket 61 and extend therefrom generally along the cylinder 41 andpiston rod 56 toward the endless loop unit 38.

The endless loop unit 38 comprises an upstanding actuating, or doordrive shaft 69 (FIGS. 2 and 3) located 74 is fixed on the shaft 69 by ahub 76 in a conventional manner, between the bearings 71 and 72. Arotatable idler member 78 of similar type but smaller diameter issupported in horizontal, coplanar relation with the member 74 adjacentand between the piston rod 56 and springs 66 and 67. In the preferredembodiment shown, the idler 78 is rotatably secured atop a support 79(FIG. 3) carried by and fixed to the bottom wall 29 of the housing. Anendless loop member 81 snugly encircles the members 74 and 78 andpositively drives the former. The endless loop member 81 may be aconventional chain and the members 74 and 78 may be sprockets. However,in the particular embodiment shown, the member 81 is a toothed timingbelt and members 74 and 78 are correspondingly toothed pulleys, thetiming belt and pulleys being of known type. The free ends of the pistonrod 56 and springs 66 and 67 are fixed to the outer surfaces of oppositereaches 84 and 85, respectively, of the belt 81 between the pulleys 74and 78 and by means of suitable clamps or brackets 87 and 88,respectively.

A drive linkage 91 couples the lower end of shaft 69 to the door 16 andcomprises a pair of pivotally connected links 93 and 94. The free end oflink 93 is removably fixed to the lower end of shaft 69 as generallyindicated at 96 and by any convenient means. The free end of link 94 ispivotally secured at 97 to a bracket 98 fixed to the interior face ofdoor 16 at the top thereof and is spaced inboard from the hinged edgethereof.

As generally indicated in FIGS. 4-6, the pressure fluid cylinder 14includes an elongate, hollow, cylindrical wall 101 extending coaxiallybetween the end walls 43 and 44 and defining a hollow, elongate pistonchamber 102.

The bosses 46 and 47 are hollow and define a back check chamber 104 anda latch check chamber 105. The chambers 104 and 105 communicatecoaxially withthe piston chamber 102 through guide openings 106 and 107,respectively and open through the free ends of the bosses 46 and 47 viacoaxial ports 108 and 109. The port 109 is provided with an annular seal110 sized for slideably receiving piston rod 56 therethrough.

The interior end (leftward in FIG. 4) of piston rod 56 coaxially carriesa radially enlarged piston 112 reciprocable between the ends of chamber102. Radially extending seal members 113 on the piston 112 slideablyengage the cylinder wall 101 to prevent leakage past the piston 112. Thepiston rod 56 further includes a pair of radially enlarged, coaxial camportions 116 and 117, which extend leftwardly and rightwardly from thepiston 112 and are snugly but slideably receivable through guideopenings 106 and 107, respectively. Annular seals 118 and 119 areprovided within the bosses 46 and 47, adjacent the guide openings 106and 107, for sealingly engaging the cam members 116 and 117,respectively, when the piston rod is respectively adjacent its leftwardand rightward extremes of travel. The remote ends 121 and 122 of cammembers 116 and 117 are tapered, the former being rounded at its endextremity.

. through which is controlled by a threaded, axially adjustable needlevalve 128. An outlet opening 130 is provided on the needle 'valve sideof the orifice 129 whereby the rate of air flow through the opening 130,orifice 129 and passage 125 may be controlled by the setting of theneedle valve 128.

The valving 33, as shown diagrammatically in FIG. 4, includes a casing133, here shown as fixed to the end wall 44 and boss 47, which through aconduit 134 communicates with a solenoid valve assembly 135. The latchcheck chamber 105 communicates directly through a port 136 with conduit134. An eccentrically located passage 138 communicates between thepiston rod (rightward in FIG. 4) end of chamber 102 and conduit 134 andcontains, in parallel, a restrictive orifice unit 140 and a one-wayvalve 142. The restrictive orifice unit 140 is preferably similar to therestrictive orifice unit 124, above described, including a similarrestrictive orifice, needle valve and opening in series. The one-wayvalve 142 is oriented to allow free air flow from the conduit 134therethrough into passage 138, but to positively prevent reverse flow,and may, for example, comprise a conventional ball check valve.

The solenoid valve assembly 135 comprises a casing 146 having a chamber147. A reciprocable plunger, or valve element 144, is slidable in thechamber 147. The conduit 134 communicates with the chamber 147. A sourceS of pressure fluid, of any conventional nature, here capable ofsupplying pressurized air at 40psi, communicates through a conduitschematically indicated at 149 and a passage 150 with the chamber 147.The passage 150 is, in the rest position of the apparatus, normallyclosed by the solenoid plunger 144.

In the preferred embodiment shown, a conventional thermally actuablevalve TV is interposed in the conduit 149 and is responsive to firewithin the building for venting the passage 150 and preventingapplication of air pressure from the source S thereto. Normally however,the valve TV simply acts as a part of the conduit 149, conveyingpressurized air from the source S to passage 150.

A further restrictive orifice unit 152, preferably similar to the unit128 above described, connects through a further passage 154 with thesolenoid valve chamber 147. A further oneway valve 155 (e.g. a ballcheck valve) connects between passage 154 and the atmosphere, to allowfree air flow into passage 154 but block reverse flow therethrough. Thepassage 154 is closeable by the solenoid plunger 144 upon actuation of asolenoid 156 (as shown in FIG. 5).

The solenoid 156, as schematically indicated in FIGS. 4 and 5, is of theelectrically actuated, springreturn type and the valve element 144, asshown by dotted line 158, is preferably connected to, or forms a partof, the movable solenoid element 159.

In the preferred embodiment shown, the door operator structure abovedescribed is controlled by electrical circuitry shown schematically inFIG. 7. AC operating potential from any convenient source, for example aconventional 110 volt AC source, is applied through a voltage reductionand/or isolation transformer 161 to an AC line 162 and, through a mainpower on-off switch 163, to a further AC line 164. Conventional treadle,or mat, operated switches, comprising an actuating switch 166 and asafety switch 167, are provided on opposite sides of the door 16, thedoor 16 normally being arranged to swing over the safety mat and awayfrom the actuating mat, as shown. The AC lines 162 and 164, mat switches166 and 167 and opening solenoid 156 are connected to the variable timedelay door control circuit 34 preferably through a separablemultiterminal connector 169.

The control 34 includes a double-pole, double-throw relay RRl,incorporating a winding W1 and two double-throw switches S1 and S1, eachhaving a movable contact and upper and lower alternatively selectablefixed contacts. The'control 34 further includes singlepole, single-throwrelays RR2 and RR3 having actuatable windings W2 and W3. The movablecontacts of switches S1 and S1 are in their downward position shown andthe contacts of relays RR2 and RR3 are open in the rest condition of thecontrol. The AC line 164 connects to the winding W1 and lower fixedcontact of switch S1. The movable contacts of switch S1 and switch S1connect across winding W2. The lower fixed contact of switch S1 connectsthrough a line 170, and the actuating switch 166 to the other AC line162. Thus, closure of the actuating switch 166 completes a circuitthrough line 170, switch S1, the winding W2 and switch S1 to the AClines, thus energizing winding W2.

A diode 172, parallelled by a surge protector, 173 connects from AC line162 to the fixed switch contact of relay RR2 and through a capacitor 174to the other AC line 164.

A transistor T1 is connected at its emitter to AC line 164 and at itscollector through winding W3 and a resistor R6 to the cathode of diode172 and thence to the other AC line 162. Thus, DC potential is appliedthrough this path to the transistor T1. The movable contact of relay RR2connects through series resistors R3 and R4 to the base of transistorT1. A point between the resistors R3 and R4 connects through a capacitorC2, paralleled by a series resistor R2 and potentiometer R1, to AC line164. Thus, closure of the contacts of relay RR2 by actuation of thewinding W2 applies positive bias from the diode 172 to the base oftransistor T1, rendering same conductive through the winding W3 of relayRR3.

The normally open contact of relay RR3 connects in series with aresistor R5 from the AC line 164 to the gate of a triac D2. The mainelectrodes of triac D2 connect from the AC line 164 through a line 176and the opening solenoid 156 to the other AC line 162. Thus, uponactuation of the coil W3, the contact of relay RR3 applies gatepotential from the AC line 164 to the triac D2, rendering sameconductive through the solenoid 156 to energize the latter.

The winding W1 of relay RRl connects from AC line 164 through a line 177and safety switch 167 to the other AC line 162. The AC line 162 alsoconnects to the upper fixed contacts of switch S1 in relay RR1. A line178 connects the upper contacts of switch S1 to the lower end of triacD2.

OPERATION To ready the door operator for operation, the power switch 163(FIG. 7) is closed, providing AC operating potential across lines 162and 164. The door 16 is normally closed and the remaining switches ofthe circuitry of FIG. 7 are in their solid-line positions shown. Thepiston rod 56 of the pressure fluid cylinder is in its extended positionshown in FIGS. 4 and 2 and the sole noid 156 is in its unenergized stateof FIG. 4.

Considering the normal operation of the door operator, a personapproaching the closed door 16 (FIG. 7) from the outside steps on theactuating mat (preferably immediately in front of the door), closing theactuating switch 166. This completes the circuit between the AC linesthrough switch S1, winding W2 and switch 81, thereby energizing windingW2 to close the contacts of relay RR2. Such closure supplies positivebase bias from AC line 162 through diode 172 and resistors R3 and R4 totransistor T1. Transistor Tl then conducts from AC line 162 throughdiode 172, resistor R6, the winding W3 and thence to the other AC line164, energizing winding W3. Closure of the relay RR2 contact alsoapplies charging current to capacitor C2 causing the lower plate thereofto rapidly accummulate a positive charge.

The energized winding W3 closes the contact of relay RR3, applying gatepotential to the triac D2 through resistor R5 from AC line 164 andrendering the triac conductive. The conductive triac D2 connectsoperating solenoid 156, through line 176 across the AC lines 162 and164, thus energizing such solenoid.

Energization of solenoid 156 shifts the plunger 144 thereof rightwardlyfrom its at rest position shown in FIG. 4, to its position of FIG. 5.Thus, pressurized air from source S enters the casing 146 throughpassage 150, passes the solenoid plunger 144, and moves through conduit134 into the casing 133. Such air then passes freely through one-wayvalve 142 and eccentric passage 138 into the rightward end of thechamber 102 to move the piston 112 leftwardly, retracting piston rod156. Such air from conduit 134 also passes freely through latch checkport 136 and into the latch check chamber 105, acting on the cam portion117 to assist in driving the piston 112 leftwardly and removing the cam117 from the latch check chamber. Air pushed leftwardly, ahead of thepiston 112, freely exits the chamber 102 through the free flow port 108,and to an extent through the orifice unit 124.

As the piston rod 56 nears the left end of its stroke, the nose 121 ofcam 116 (FIG. 6) passes through the guide opening 106 and seal 118 intothe back check chamber 104, at first partly, then completely, preventingair pushed ahead of the retracting piston 112 from exiting chamber 102through the free flow port 108. Thereafter, such air can only exit thechamber 102 at a controlled, low rate through the restrictive orificeunit 124. This causes the retracting piston rod 56 to slow smoothly,over a substantial portion of its travel, until it comes to rest withthe piston 112 adjacent the leftward, or blind, end of the cylinder 41.

As seen in FIGS. 2 and 3, such retraction of the piston rod 56 pulls theupper reach 84 of the belt 81 toward the idler pulley 78, orbiting thebelt 81 (clockwise in FIG. 2) and moving the lower reach 85 of the beltleftwardly, pulling the clamp 88 leftwardly and tensioning and extendingsprings 66 and 67. Such orbiting of the belt also positively rotates theguide pulley 74 and shaft 69 to rotate the link 93 clockwise to itsbroken line position 93'. This in turn pulls the link 94 downwardly andleftwardly (FIG. 2) to open the door 16. Thus, as piston rod 56decelerates gradually to a stop in its retracted position, the door 16decelerates smoothly to its open position 16', remote from a personstanding on the actuating mat (FIG. 7).

The apparatus will stay in its state Iast'mentioned. with the door open,while the person walks or stands on the actuating mat 166. Normally,however, upon opening of the door, the person will advance through theopen doorway and onto the safety mat 167. As the person leaves theactuating mat, the switch 166 opens, deenergizing relay RR2. However,transistor T1 remains conductive for a delay period determined by thedischarge time of capacitor C2 through resistor R2 and potentiometer R1.Thus, W3, triac D2 and solenoid 156 remain actuated during this delay.The length of the delay is adjustable by potentiometer R1. This delaygives the person a sufficient time to pass through the open doorwaybefore the door 16 closes.

A person so passing through the doorway then normally steps on thesafety mat, closing the switch 167 within such delay period. Thus, thewinding WI of relay RR] is energized through safety switch 167 across AClines 162 and 164 and shifts the contacts of switches S1 and S1 upwardlyto their dotted line positions of FIG. 7. In consequence, current flowsthrough the AC line 162, switch S1, winding W2, switch S1, line 178, thestill conductively biased triac D2 and the remaining AC line 164. Theresultant reenergizing of winding W2 closes the relay RR2 contact toreestablish the charge on capacitor C2, and continues to bias transistorT1 and thereby continue conduction of triac D2 while the safety switchremains closed. This continues energization of the solenoid 156 to holdthe door open.

As the person leaves the safety mat, the safety switch 167 opens. Suchremoves AC potential from winding W1, allowing switches S1 and S1 toreturn to their solid line positions of FIG. 7 and deenergizing windingW2. After capacitor C2 discharges through the time delay period,transistor T1 shuts off, deenergizing winding W3, whereafter the triacD2 shuts off, deenergizing solenoid 156. The delay period is sufficientto allow the person to move well beyond the safety mat and out of thepath of the door 16.

Upon deenergization of the solenoid 156, the movable solenoid elementreturns to its rest position, by means of a suitable spring in a knownmanner, shifting the valve element 144 leftwardly to its position ofFIG. 4, preventing supply of pressurized air from source S to theconduit 134, and opening the conduit 134 to the restrictive orifice unit152.

The piston rod 56 is then free to return rightwardly from its retractedposition of FIG. 6. The tension springs 66 and 67 (FIGS. 2 and 3) thencontact, pulling the lower reach of belt 81 rightwardly, orbiting thebelt 81 counterclockwise, and moving the upper reach 84 leftwardly. Suchpulls, or extends, the piston rod 56, rotating the drive pulley 74counterclockwise to cause the link 93 to return the door 16 to its fullyclosed position.

During such piston rod extension, the piston 112 (FIGS. 4 through 6)moves rightwardly, drawing air behind it into chamber 102, primarilythrough the free flow port 108. Air pushed ahead of the moving piston112 flows freely through latch check chamber 105, port 136, conduit 134and then, in a restricted manner, out the restrictive orifice unit 152.Thus, the unit 152 limits the maximum closing speed of the door.

As the piston rod 56 nears full extension, the tapered nose 122 of cam117 enters the guide opening 107, the taper of the nose 122progressively restricting air flow into the latch check chamber 105 andgradually decelerating the piston rod. After the nose 122 has passed theseal 119, no further air can be pushed by piston 112 into the latchcheck chamber 105 and all air pushed ahead of the piston 112 must flowinto port 138 and thence through restrictive orifice unit 140 (theoneway valve 142 being positively closed to air flow in this direction).Thus, restrictive orifice unit 140 further restricts exhaust air flow,further slowing and extending piston rod 56 and closing door so that thelast increment of closing door movement is gradual. The chambers 104 and105 (FIG. 4) and corresponding cam members 116 and 117 are relativelylong, compared to the total stroke of the piston rod 56 (here totallingabout one-third of said stroke length), so that deceleration of the dooras it approaches the ends of its travel is indeed gradual.

This completes the normal opening and closing cycle of the door operatorof FIGS. 1 through 7.

If, at any time during the opening and closing cycle of the door, theactuating switch 166 is again closed, the cycle immediately begins anewand proceeds in the manner above discussed.

To avoid the possibility of the door opening and striking a person inits path, the safety mat normally covers the area near and swept by theopening door. Thus, a person adjacent the closed door, standing in itspath and on the safety mat, will close the safety switch 167. With theapparatus of FIGS. 1 through 7 in its rest position shown (door closed,triac D2 off), closure of the safety switch 167 has no effect on thedoor. More particularly, closure of the safety switch 167 will energizewinding W1, switching the contacts of switches S1 and S1 to their dottedline positions, and thereby coupling winding W2 in series with triac D2across the AC line 162 and 164. However, triac D2, being off, cannotsupply current to winding W2. In consequence, transistor T1, relay RR3and the triac D2 remain nonenergized and the door does not open.Further, while the safety switch 167 is closed, closing of actuatingswitch 166 has no effect since switch S1 no longer couples the line 170to the winding W2. Thus, actuation of the safety switch 167 preventssubsequent closing ofthe actuating switch 166 from opening the door.

With the provision of the thermal valve TV, above discussed, the door 16can be used as a fire door. More particularly, the door normallyfunctions as an automatic door (as above described), but in case of firewould be relieved of air pressure from source S by the thermal valve TV,whereby the springs 66 and 67 would resiliently urge the door to itsclosed position and the door would no longer be opened by switches 166.On the other hand, the door could be manually opened in such instances(or in any other instances wherein air pressure is not supplied to theconduit 134 from the source S) by manually pulling, or pushing, open thedoor 16 against the reslient force of the springs 66 and 67, atmosphericpressure being maintuined behind (to the right in FIG. 4) the piston 112by, for example, leakage through the check valve 155.

For emergency use, an emergency switch, not shown, may be provided, forexample in series with the solenoid 156 across the AC lines 162 and 164,for energizing such solenoid to open the door.

The door operator embodying the invention can, in the absence of airsupply to the cylinder 41, be employed as a resilient door closer with achecking, or door decelerating, action toward the end of the doorclosing movement. Under such conditions, the door can be opened manuallyagainst the force of the springs 66 and 67.

It may be desired, or required by local building codes, that the doorrequires no more than a specified maximum force to open in the event offailure of its automatic operator. Thus, should the timing belt 81 (FIG.2) become immobilized, the guide pulley 74, in response to a preselectedand greater than normal torque on the shaft 69 and door, will slip withrespect to the belt, allowing opening or closing of the door. A similareffect can be achieved in FIG. 10, hereinafter discussed, by providing apresettable slip clutch of conventional type (not shown) between thesprocket 74C and shaft 69C, for example.

If desired, the ratio of pressure fluid cylinder stroke and door openingangle can be varied, as for example by interposing a ratio changing geartrain or the like between the driven pulley 74 and shaft 69, or moresimply, by changing the diameter of the pulley 74 or the length of link93 or the location of bracket 98.

MODIFICATIONS The operator embodying the invention can be used withdoors of either hand, that is, doors hinged at either their left orright sides. While FIG. 2 shown the operator 20 used with an inwardlyswinging door 16 hinged at its left side, FIG. 8 discloses the operator20 rearranged for operating a door 16A hinged at its right side, asindicated at 17A. Such is accomplished by rotating the door operator 20about an axis perpendicular to the wall 11 through 180, so that thedrive pulley 74 is adjacent the hinge 17A. The linkage 93, 94 is thenconnected to the other exposed end of the shaft 69, now extendingdownwardly. Thus, the same operator 20 can be used with both left-handand right-hand hinged doors simply by a rotation thereof andreconnection of the linkage 93, 94.

As shown in FIG. 9, the operator 20 can also be used with an outwardlyswinging door 168 of either hand, here for example left-hand hinged at178. To accomplish this conversion, the bracket 61 is disconnected fromthe housing walls and rotated 180 degrees about a vertical axis andreconnected, to place the bight 65 thereof adjacent the housing backwall 24 instead of the front wall 25. The springs 66, 67 and piston rod56 are disconnected from belt 81. The fluid cylinder 41 is then pivotedon pivot 54 toward the front wall 25 of the housing to place the pistonrod 56 in front of idler pulley 78. To facilitate such shifting, theidler pulley 78 may be temporarily removed. Thereafter, the springs 66,67 are connected to the reach 84 (in back of the fluid cylinder 41) andthe piston rod 56 is connected to the front reach 85 of the belt. Inthis way, the retracting piston rod 56 and spring pair 66, 67 willrotate the drive pulley 74 in reversed directions as compared to theirarrangement of FIG. 2. Longer links 93B and 94B may replace the links 93and 94 of FIG. 2. Thus, retraction of piston rod 56 will still open thedoor 16B, as in FIG. 2, but by rotation of pulley 74 in the oppositedirection.

It will be understood that the operator 20, arranged as in FIG. 9, canbe rotated through about an axis perpendicular to the building wall andwith repositioning arm 938 at the other end of shaft 69, can be usedwith right-hand hinged, outwardly swinging doors.

Thus, the same door operator assembly can accommodate all of the fourpossible combinations of door hinging and opening directions, i.e.,right-hand hinge, left-hand hinge, interior opening, and exterioropening.

In FIG. 10, a modified door operator 20C is disposed in a space in thewall between stiles 13C and 14C and in overlapping fashion above thedoor (indicated in a broken line at 16C in its normal closed position).The operator housing 22C is fixedly located, for example by securementto stile 13C and 14C, by any convenient means not shown. The modifieddoor 16C is of the type pivotally supported by coaxial shaft offsetinboard from the edge of the door and extending vertically upwardly anddownwardly therefrom, the shafts being pivoted, for example, in asuitable socket, not shown, in the building floor and/or in the areadirectly above the door. In the particular embodiment shown, theupwardly extending door pivot shaft connects to or is in extension of ashaft 69C, rotatably supported by the housing 22C as in FIG. 3. Thus,rotation of the shaft 698 rotates the door 16C to and from its openposition shown in 16C, in response to rotation of the drive member 74C.

The door operator 20C of FIG. is further modified in that members 74Cand 78C comprise sprockets and the endless loop member 81C comprises achain.

It should be noted that the direct drive arrangement of FIG. 10 requiresa lesser angle of rotation by drive member 74C to affect a given angle(for example 90) of door pivotal motion, the angle of rotation of thedrive member 74C and door being the same in FIG. 10. In contrast, thedrive member 74 of FIGS. 2, 8 and 9 may traverse an angle between 90 andl80 for a 90 opening movement of the corresponding door. Thus, apressure fluid cylinder of shorter stroke or a larger drive memberdiameter may be employed in the modified FIG. 10 apparatus.

FIG. 11 discloses a modified door operator D similar to the operator 20but adapted for use in opening and closing a sliding door 183. Theoperator 20D is located above the upper track 185 of the sliding doorand except as in hereinafter discussed basically comprises the dooroperator 20 as shown in FIG. 8 but rotated about its length axis throughan angle of 90 and so that the drive shaft 69D is horizontal and has oneend thereof forwardly overhanging the front face of the door 183. Thedoor 183 has fixed to its upper rightward face a vertical track element187 having a longitudinal undercut groove. A link 93D is fixed to theexposed end of shaft 69D and extends therefrom into pivotal connectionwith a slider 188 vertically slidable within the track element 187.Thus, upon counterclockwise rotation of the shaft 69D, the link 93Dswings, thus simultaneously sliding downward along the track element 187and causing the door 183 to slide rightwardly along its track to itsopen position indicated in broken lines at 183'. Reversal of therotation of the shaft 69D reverses the sliding motion of the door 183 toreturn same to its closed solid line position of FIG. 11.

The operator 20 can thus also be arranged to actuate gates and foldingdoors, in the latter instance, for example, either panel of aconventional, hinge connected bifold door pair.

FIGS. 12 and 13 disclose a modified door operator system 191 for openingand closing a double, or tandem, door arrangement, comprising a pair ofdoors 16E and 16F. Such doors 16E and 16F when closed are substantiallycoplanar and are hinged at 17E and 17F at their remote side edges onstiles 14E and 13E, respectively. The double door operator 191 includesan elongate housing 192 mounted on the stiles 13E and ME, as in FIG. 2.A single door operator unit 20E, arranged as in FIG. 8, is provided atone end of the housing 192, here the rightward end as diagrammaticallyindicated in broken lines. The door operator 20E is arranged within thehousing 192 and opens and closes the door 16E in the same manner abovedescribed with respect to FIGS. 2 through 9.

In addition, however, a dislike synchronizing member 198 is fixed to theupper end of the shaft 69E for rotation therewith. In the particularembodiment shown, member 198 is a sprocket. The lower end of the shaft69E, as in FIG. 8, is connected through links 93E and 94E to the door60E.

A similar shaft 69F is rotatably supported at the opposite end ofhousing 192 by suitable bearings not shown, as in FIG. 3. The lower andupper ends of shaft 69F extend beyond the top and bottom walls of thehousing 192 and respectively fixedly carry a link 93F (which as in FIG.2 connects through a further link 94F to door 16F) and a furthersynchronizing member, or sprocket 199, preferably identical to themember 198. Flexible positive drive elements 201 and 202, here lengthsof chain, partially encircle sprockets 198 and 199, respectively and arein positive driving relation therewith. Crossed cables 203 and 204 jointhe diagonally opposed ends of chains 201 and 202 to provide a closedloop of Figure-eight configuration which is maintained under moderatetension, hereby a turnbuckle l06 in cable 203.

Thus, rotation of shaft 69E by the door operator 20E, by rotation ofsprocket 198, orbiting of chains 201, 202 and cables 203, 204 effectsequal and opposite rotation of sprocket 199 and hence of shaft 69F.Thus, shafts 69E and 69F rotate in opposite directions and insynchronism to effect a shychronized opening or synchronized closing oftheir corresponding doors 16E and 16F.

If desired, in cases where for example the doors 16E and 16F arerelatively heavy or have relatively high pivot friction, an additionaloperator, not shown, arranged in a manner of operator 20 of FIG. 2, maybe provided at the left end of housing 192 to rotatably drive the shaft69F for opening and closing door 16F, the synchronizing apparatus 198through 206 maintaining synchronous opening and closing of the two doorsdespite the use of two separate operators.

FIGS. 14 and I5 disclose a modification providing for power assisteddoor closing and usable, for example, in high stack pressure situationswherein the normal springs 66 and 67 (FIG. 3) may be insufficientlystrong as to close the door. Such modification can be either factory orfield installed.

FIG. 14 discloses a piston rod 56 of cylinder 41 in an intermediateposition of door closing movement and is modified from the structureshown in FIGS. 4-6 as follows.

A further solenoid valve assembly 208 comprises a casing 209 containinga chamber 210. A reciprocable valve element 211 is slidable in thechamber 147 to alternatively close an exhaust port 213 (during doorclosing movement, as shown in FIG. 14) and a pressure fluid inlet port214 (during door opening movement). The exhaust port 213 may ventdirectly to the atmosphere. The inlet port 214 connects through anadjustable orifice, or valve 216, control valve 16, and a conduit 217 tothe source S of pressurized air, as schematically indicated in FIG. 14.A conduit or passage 219, connects the chamber 210 to the free flow port108 of cylinder 41, above described, and also to the port 130 of therestrictive orifice unit 124, above described.

FIG. discloses a fragment of the circuit of FIG. 7 modified by theaddition of a closing solenoid circuit 221. Such circuit 221 includes arelay RR4 having a winding W4 energizable for opening a single-pole,single-throw switch S4. The winding W4 connects through lines 176A and162A across the opening solenoid 156 above discussed with respect toFIG. 7. A line 164A connects from AC line 164 through switch S4, aclosing solenoid 222 and line 162A to the other AC line 162. The closingsolenoid 222 is suitably mechanically connected, as schematicallyindicated by broken line 223 in FIG. 14, to the valve element 211.

Thus, when the opening solenoid 156 is energized (to open or hold openthe door) as above discussed, the winding W4 is similarly energized toopen switch S4, whereby closing solenoid 222 is deenergized. When suchsolenoid is deenergized it locates the valve element 211 in its leftwardposition (FIG. 14) closing the pressurized air inlet 214 and opening theexhaust port 213. Thus, air pushed ahead of the leftwardly moving (FIG.14) piston 112 escapes the cylinder 41 through port 108, and to a lesserextent through restrictive orifice unit 124, and thence through passage219 past the valve element 211 and out exhaust port 213.

On the other hand, when opening solenoid 156 is deenergized so also iswinding W4 (FIG. 15) and switch S4 is closed, energizing closingsolenoid 222 by connecting same across the AC line 164 and 162. Theenergized solenoid 222, through the connection 223 (FIG. 14) shifts thevalve 211 to its rightward position shown in FIG. 14, closing exhaustport 213 and opening the passage 214. Air then flows from thepressurized source S through conduit 217, at a rate controlled by thespeed control valve 216, and thence through port 214 and passage 219 tothe port 108 (and to the lesser extent through restrictive orifice unit124) and thereby into the leftward (FIG. 14) end of the cylinder 41 toassist the springs 66 and 67 (FIG. 3) in extending the piston rod 56, soas to close the door.

Although particular preferred embodiments of the invention have beendisclosed in detail for illustrative purposes, it will be recognizedthat variations or modifications of the disclosed apparatus, includingthe rearrangement of parts, lie within the scope of the presentinvention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. In a door operator for a door movable between an opened position anda closed position, the combination comprising:

a flexible endless loop member and door drive shaft means direct drivenin opposite directions thereby for opening and closing said door;

motor means engaging a reach of said endless loop member and actuablefor moving said endless loop member in one orbital direction;

return means also engaging a reach of said endless loop member andresponsive to disabling of said motor means for closing said doorthrough moving said endless loop member in the opposite orbitaldirection;

whereby said motor means and return means oppositely orbit said endlessloop member to move said door between open and closed positions.

2. The apparatus of claim 1 in which said door drive shaft meansincludes a door drive shaft and a rotatable drive member fixed thereonand including a freely rotatable idler spaced therefrom by said reaches,said flexible endless loop member encircling said idler and drive memberand positively engaging and rotatably driving said drive member, saidmotor means and said return means respectively comprising a pressurefluid cylinder energizable for retraction and a tension spring, each ofwhich has an end directly connected to said endless loop memberintermediate said drive member and idler, and means coupling saidrotatable drive member to said door for opening and closing same uponopposite orbital movement of said loop member by said cylinder andspring.

3. The apparatus of claim 1 in which said motor means includes apressure fluid cylinder having a retractable piston rod connected tosaid endless loop member for moving said door, a piston on said pistonrod and responsive to pressure on one side thereof for moving saidpiston rod in one direction, oppositely directed cam means on saidpiston rod and chamber means at opposite ends of said cylinder graduallyblockable by respective cam means for gradually initially deceleratingthe piston rod before nearing the ends of its stroke, and valve meanscontrollable for applying pressure fluid to said piston rod to move samein said one direction.

4. The apparatus of claim 3 including first restrictive orifice meansparalleling the said chamber means at one end of said cylinder forfurther decelerating said piston as it approaches said end of saidcylinder in the final part of its stroke, valve unit means at theopposite end of said cylinder and a conduit in communication with saidvalve unit means, said valve unit means including a second restrictiveorifice and a one-way valve both connected in parallel between saidconduit and said opposite cylinder end, said one-way valve allowing freefluid flow from said conduit to said piston but positively blockingreturn flow thereby except return flow through said second restrictiveorifice, said valve unit means further including a passage communicatingbetween said conduit and the adjacent other said chamber means inparallel with said second restrictive orifice and one-way valve.

5. The apparatus of claim 4 including a pressure fluid source and thirdrestrictive orifice means alternatively communicable with said conduitpast said controllable valve means, said controllable valve meansincluding a plunger movable for alternately blocking said source andthird restrictive orifice means.

6. The apparatus of claim 1 including electrically energizable means foractuating said motor means, control circuit means responsive toactuation of an actuating switch for energizing said electricallyenergizable means and for maintaining said energization for apredetermined delay time following the deactuation of said actuatingswitch.

7. The apparatus of claim 6 including switch means responsive toactuation of a safety switch for causing said control circuit means tohold said door open in response to prior actuation of said actuatingswitch occurring within said delay time but for preventing opening ofsaid door in response to a subsequent actuation of said actuatingswitch.

8. The apparatus of claim 1 including a housing supporting said endlessloop member, motor means and return means adjacent said door, said doordrive shaft means comprising a shaft rotatably supported in said housingand having both ends thereof extending from said housing, meansconnecting one extended end of said shaft to said door for opening andclosing said door upon opposite rotations of said shaft, said dooroperator being usable with both rightwardly and leftwardly hinged doorsby rotation of said housing through 180 about an axis transverse to theplane of the closed door and using of the opposite extended shaft endfor opening and closing connection to said door.

9. The apparatus of claim 1 including a housing carrying said endlessloop member and motor means and return means, said housing being offsetvertically of said door width-wise of the door opening, said motor meansincluding an elongate reciprocable member secured to said endless loopmember, said return means comprising an elongate resilient membersecured to said endless loop member, said endless loop beinglongitudinally extended lengthwise of said housing, said reciprocablemember and said resilient member end engaging said endless loop memberand extending along said reaches and longitudinally of said endless loopmember to opposite ends secured to the housing remotely of said endlessloop member for urging said reaches of said endless loop member inopposite rotational directions.

10. The apparatus of claim 9 in which said resilient member comprises anelongate tension spring and including bracket means on said housing andspaced from said endless loop member, said resilient member beingsecured adjacent its free end to said bracket means for rotating saidendless loop member when tensioncd and in the absence of actuation ofsaid motor means.

11. The apparatus of claim 10, in which said motor means comprises apressure fluid retraction cylinder, said reciprocable member comprisingthe piston rod thereof, said cylinder being located remotely of saidendless loop member and including means pivotally mounting the free endof said cylinder on said housing for permitting pivotal movement of saidpressure fluid cylinder during retraction of said piston rod. 12 Theapparatus of m'ir'rfivmar said bracket means is reversibly mounted onsaid housing, said pressure fluid cylinder and spring normally extendingsubstantially in parallelism along and beyond opposite reaches of saidendless loop member, said reaches extending substantially longitudinallyof said housing, whereby said door operator is adaptable to use witheither inwardly or outwardly swinging doors by reversal of said bracketmeans on said housing and pivoting of said pressure fluid cylinder toallow reversed securement of said piston rod and spring to said endlessloop means.

IS. The apparatus of claim 12 in which said endless loop member issecured to said spring and piston rod ends on opposite reaches thereof,said door drive shaft means including a rotatable drive member and theshaft thereof rotatably supported on said housing and spaced away fromsaid spring and rod ends, said shaft being driven by said endless loopmember directly through said rotatable drive member and fixedly carryinga first link, a second link pivotally engaging said first link and saiddoor, whereby rotation of said shaft results in opening and closingmovement of said door, the length of said links being variable foradapting said operator to either inwardly or outwardly swinging doors.

14. The apparatus of claim 1 including a spaced pair of rotatablemembers around which said endless loop member orbits, said endless loopmember being in positive driving engagement with one said rotatablemember, a housing disposed directly above said door, said door driveshaft means incorporating said one rotatable member, a shaft fixedlyengaging said door on the hinge axis thereof and extending rotatably andupwardly into said housing, said shaft fixedly engaging said onerotatable member, whereby orbiting of said endless loop member opens and15. The apparatus of claim 1 in which said door is a sliding door, saidendless loop member being supported in a substantially vertical planeabove said sliding door and including a rotatable idler, said door driveshaft means consisting of a shaft and a rotatable drive member carryingsaid endless loop member in cooperation with said idler, said endlessloop member directly driving said rotatable drive member, a link fixedto said shaft and a substantially vertical guide track on said doorslidably engaging said link, whereby rotation of said drive memberslides said door between open and closed positions.

16. The apparatus of claim 1 in which said door comprises a pair ofsubstantially alignable door panels hinged at remote side edges thereof,said door operator including a housing adjacent the tops of said doorpanels, a pair of rotatable synchronizing members on said housingadjacent opposite ends thereof, one said synchronizing member beingfixed on said door drive shaft means, an elongated loop twisted todefine substantially a figure-eight configuration and passing aroundsaid rotatable synchronizing members for constraining said members torotate in synchronism and in opposite rotational directions, a firstoperator unit comprising said endless loop extending from said driveshaft means in overlapping relation with said figure-eight loop, saidmotor means and return means respectively comprising respective poweredand resilient elongate retractable members extending from the reaches ofsaid endless loop member below said figure-eight" loop.

17. The apparatus of claim 16 including a second door operator unit ofsimilar kind and reversed orientation having a positive drivingconnection to the other of said synchronizing members and door panel.

18. The apparatus of claim 5 including a further oneway valve connectedin parallel with said third restrictive orifice means to saidcontrollable valve means and oriented to positively block pressure fluidflow therethrough from said controllable valve means but to freely allowfluid flow therethrough toward said controllable valve means, whereby,when said controllable valve means is positioned to block communicationbetween said source and said conduit, and said piston is moving towardsaid one end of said cylinder, said further one-way valve maintainsatmospheric pressure behind said piston.

19. The apparatus of claim 3 including further valve means controllablefor applying pressure fluid to said piston rod to move same in saidopposite direction for assisting said return means and including asolenoid controlled valve having a valve element shiftable foralternatively allowing exhaust fluid movement out of said cylinder aheadof the piston rod as the latter moves in said one direction for openingthe door and for applying pressure fluid to said piston to assist movingsame in said opposite direction during door closing movement.

20. The apparatus of claim 19 in which said controllable valve meansincludes an opening solenoid ener-- gizable for causing pressure fluidto move the piston rod in said one direction and in which said furthervalve means includes a closing solenoid and a relay for controllingactuation of said closing solenoid, said relay being connected inparallel with said opening solenoid and adapted to energize said closingsolenoid in alternative relation to energization of said openingsolenoid.

21. The apparatus of claim 19 in which said further valve means includesa speed control valve in series with saidsolenoid controlled valve.

22. The apparatus of claim 9 including pivot means for securing saidopposite ends of said reciprocable member and resilient member in saidhousing and a freely rotatable idler, said endless loop member havingextremities rbi allxsupe lsi sais id ctan driv shaft means, said pivotmeans and door drive shaft means being spaced in opposite directionslongitudinally of the housing from said idler, said reciprocable membercomprising longitudinally extended linear actuator means actuable forretraction and said resilient member comprising a tension spring, thefirst mentioned ends of said retractable linear actuator means andspring being fixed to opposite reaches of said endless loop means andextending therealong away from said drive shaft means foralternativelytensioning said loop means around said door drive shaft means.

23. The apparatus of claim 3 including valving means connected to theone of said cylinder ends approached by the piston rod moving in saidone direction for controlling fluid flow to and from said one chambermeans, a valve unit at the other end of said cylinder, and meansdefining a flow path between said valving means and said valve unit (1)for traveling fluid to said one cylinder end to facilitate movement ofsaid piston away therefrom in response to urging of said return meansand (2) for alternatively traveling fluid to said valve unit at saidother cylinder end during piston movement away from said other cylinderend.

24. The apparatus of claim 3 including valving means connected to theone of said cylinder ends approached by the piston rod moving in saidone direction for controlling fluid flow to and from the chamber meansat said one cylinder end, a valve unit at the other end of saidcylinder, and means defining a flow path between said valving means andsaid valve unit (1) for traveling fluid to said one cylinder end tofacilitate movement of said piston away therefrom in response to urgingof said return means and (2) for alternatively traveling fluid to saidvalve unit at said other cylinder end during piston movement away fromsaid other cylinder end.

25. In a door operator for a door movable between an opened position anda closed position, the combination comprising:

endless loop means movable in opposite directions for opening andclosing said door;

motor means coupled to said endless loop means and actuable for movingsaid endless loop means in one direction, said motor means including apressure fluid cylinder having'a retractable piston rod connected tosaid endless loop member for moving said door, a piston on said pistonrod and responsive to pressure on one side thereof for moving saidpiston rod in one direction, oppositely directed cam means on saidpiston rod and chamber means at opposite ends of said cylinder graduallyblockable by respective cam means for gradually initially deceleratingthe piston rod before nearing the ends of its stroke, and valve meanscontrollable for applying pressure fluid to said piston rod to move samein said one direction;

return means coupled to said endless loop means and responsive todisabling of said motor means for moving said endless loop means in theopposite direction;

whereby said motor means and return means act through said endless loopmeans to move said door between open and closed positions.

26. in a door operator for a door movable between an opened position anda closed position, the combination comprising:

endless loop means movable in opposite directions for opening andclosing said door;

motor means coupled to said endless loop means and actuable for movingsaid endless loop means in one direction;

return means coupled to said endless loop means and responsive todisabling of said motor means for moving said endless loop means in theopposite direction;

electrically energizable means for actuating said motor means, controlcircuit means responsive to actuation of an actuating switch forenergizing said electrically energizable means and for maintaining saidenergization for a predetermined delay time following the deactuation ofsaid actuating switch, switch means responsive to actuation of a safetyswitch for causing said control circuit means to hold said door open inresponse to prior actuation of said actuating switch occurring withinsaid delay time but for preventing opening of said door in response to asubsequent actuation of said actuating switch;

whereby said motor means and return meansact through said endless loopmeans to move said door betwen open and closed positions.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3 864 875Dated February 1 1915 a l Lew V. Hewitt It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

Col. 16, line 21; after "and" insert closes said door.-.

Col. 17, line 3; change "said" to -the.

Col. 17, lines 40 through 51; please cancel Claim 23.. 0 Col. 18, afterline 60; add the following claim:

---27. In a door operator, for a door pivotable between I Q an openposition and a closed position, the combination comprising:

a housing fixedly mountable above and adjacent said door and extendingsubstantially the width of the door opening;

a drive shaft extending through at least a bottom wall of said housingand rotatably supported on opposed top and bottom housing walls andmeans connecting said drive shaft to said door at least adjacent a pivotaxis of said door for rotating said door between open and closedpositions upon rotation of said drive shaft;

a rotatable disklike drive member fixed on said shaft USCOMM-DC60376-P69 u.s. GOVERNMENT PRINTING orncz; 869 93 0 FORM PO-105O (10-69)UNITED STATES PATENT OFFICE Page 2 CERTH ICATE 0F ;CORRECTION Patent No.3 864 875 Dated February 11, 1975 Inv nt0 Lew V. Hewitt It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

. and located in said housing;

a freely rotatable idler fixedly located in said housing remote fromsaid drive member and an endless loop member encircling said drivemember and idler in positive and toothed driving connection with saiddrive member for rotating said shaft synchronously with orbiting of saidendless loop member,

a said endless loop member having first and second reaches on oppositesides of a common diametrical line between said idler and said drivemember;

a an elongate resilient tension member and means releasably fixedlysecuring one end thereof to said housing remotely from said endless loopmember and means fixedly securing the a other end thereof to one reachof said endless loop member;

a pressure fluid cylinder adjacent said resilient member having a pistonrod extending from one end thereof into fixed Q engagement with theother reach of said endless loop member,

FORM PO-1 USCOMM-DC 60376-P69 U.$ GOVERNMENT PRINTING OFFICE: a 9 93 OFORM PO-105D (10-69) UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Page 3 Patent No. Dated ebruary ll, 1975 Inventor(s) Lew V.Hewitt It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

the other end of said cylinder being pivotally supported on saidhousing, said cylinder including means at the ends thereof incorporatingcontrollable restrictive orifices and coacting means on said piston rodfor providing controlled deceleration of said piston rod at the ends ofits stroke;

a solenoid controlled valve and a variable time delay control circuitcarried by said housing, said solenoid control valve being responsive tosaid control circuit for alternatively applying pressure fluid to saidone end of said pressure fluid cylinder for retracting said piston rodand for exhausing said last-mentioned end of said cylinder at acontrolled rate;

switches on opposite sides on said door and means coupling same to saidcontrol circuit for opening said door in response to actuation of onesaid switch, holding said door open for a controlled delay period inresponse to subsequent actuation of the other said switch within asimilar delay USCOMM-DC 60376-P69 U.S GOVERNMENT PRINTING OFFICE: o

1. In a door operator for a door movable between an opened position anda closed position, the combination comprising: a flexible endless loopmember and door drive shaft means direct driven in opposite directionsthereby for opening and closing said door; motor means engaging a reachof said endless loop member and actuable for moving said endless loopmember in one orbital direction; return means also engaging a reach ofsaid endless loop member and responsive to disabling of said motor meansfor closing said door through moving said endless loop member in theopposite orbital direction; whereby said motor means and return meansoppositely orbit said endless loop member to move said door between openand closed positions.
 2. The apparatus of claim 1 in which said doordrive shaft means includes a door drive shaft and a rotatable drivemember fixed thereon and including a freely rotatable idler spacedtherefrom by said reaches, said flexible endless loop member encirclingsaid idler and drive member and positively engaging and rotatablydriving said drive member, said motor means and said return meansrespectively comprising a pressure fluid cylinder energizable forretraction and a tension spring, each of which has an end directlyconnected to said endless loop member intermediate said drive member andidler, and means coupling said rotatable drive member to said door foropening and closing same upon opposite orbital movement of said loopmember by said cylinder and spring.
 3. The apparatus of claim 1 in whichsaid motor means includes a pressure fluid cylinder having a retractablepiston rod connected to said endless loop member for moving said door, apiston on said piston rod and responsive to pressure on one side thereoffor moving said piston rod in one direction, oppositely directed cammeans on said pistoN rod and chamber means at opposite ends of saidcylinder gradually blockable by respective cam means for graduallyinitially decelerating the piston rod before nearing the ends of itsstroke, and valve means controllable for applying pressure fluid to saidpiston rod to move same in said one direction.
 4. The apparatus of claim3 including first restrictive orifice means paralleling the said chambermeans at one end of said cylinder for further decelerating said pistonas it approaches said end of said cylinder in the final part of itsstroke, valve unit means at the opposite end of said cylinder and aconduit in communication with said valve unit means, said valve unitmeans including a second restrictive orifice and a one-way valve bothconnected in parallel between said conduit and said opposite cylinderend, said one-way valve allowing free fluid flow from said conduit tosaid piston but positively blocking return flow thereby except returnflow through said second restrictive orifice, said valve unit meansfurther including a passage communicating between said conduit and theadjacent other said chamber means in parallel with said secondrestrictive orifice and one-way valve.
 5. The apparatus of claim 4including a pressure fluid source and third restrictive orifice meansalternatively communicable with said conduit past said controllablevalve means, said controllable valve means including a plunger movablefor alternately blocking said source and third restrictive orificemeans.
 6. The apparatus of claim 1 including electrically energizablemeans for actuating said motor means, control circuit means responsiveto actuation of an actuating switch for energizing said electricallyenergizable means and for maintaining said energization for apredetermined delay time following the deactuation of said actuatingswitch.
 7. The apparatus of claim 6 including switch means responsive toactuation of a safety switch for causing said control circuit means tohold said door open in response to prior actuation of said actuatingswitch occurring within said delay time but for preventing opening ofsaid door in response to a subsequent actuation of said actuatingswitch.
 8. The apparatus of claim 1 including a housing supporting saidendless loop member, motor means and return means adjacent said door,said door drive shaft means comprising a shaft rotatably supported insaid housing and having both ends thereof extending from housing, meansconnecting one extended end of said shaft to said door for opening andclosing said door upon opposite rotations of said shaft, said dooroperator being usable with both rightwardly and leftwardly hinged doorsby rotation of said housing through 180* about an axis transverse to theplane of the closed door and using of the opposite extended shaft endfor opening and closing connection to said door.
 9. The apparatus ofclaim 1 including a housing carrying said endless loop member and motormeans and return means, said housing being offset vertically of saiddoor width-wise of the door opening, said motor means including anelongate reciprocable member secured to said endless loop member, saidreturn means comprising an elongate resilient member secured to saidendless loop member, said endless loop being longitudinally extendedlengthwise of said housing, said reciprocable member and said resilientmember end engaging said endless loop member and extending along saidreaches and longitudinally of said endless loop member to opposite endssecured to the housing remotely of said endless loop member for urgingsaid reaches of said endless loop member in opposite rotationaldirections.
 10. The apparatus of claim 9 in which said resilient membercomprises an elongate tension spring and including bracket means on saidhousing and spaced from said endless loop member, said resilient memberbeing secured adjacent its free end to said bracket means for rotatingsaid endless loop member when tensioned and in the absence of Actuationof said motor means.
 11. The apparatus of claim 10, in which said motormeans comprises a pressure fluid retraction cylinder, said rodcomprising the piston rod thereof, said cylinder being located remotelyof said endless loop member and including means pivotally mounting thefree end of said cylinder on said housing for permitting pivotalmovement of said pressure fluid cylinder during retraction of saidpiston rod.
 12. The apparatus of claim 11 in which said bracket means isreversibly mounted on said housing, said pressure fluid cylinder andspring normally extending substantially in parallelism along and beyondopposite reaches of said endless loop member, said reaches extendingsubstantially longitudinally of said housing, whereby said door operatoris adaptable to use with either inwardly or outwardly swinging doors byreversal of said bracket means on said housing and pivoting of saidpressure fluid cylinder to allow reversed securement of said piston rodand spring to said endless loop means.
 13. The apparatus of claim 12 inwhich said endless loop member is secured to said spring and piston rodends on opposite reaches thereof, said door drive shaft means includinga rotatable drive member and the shaft thereof rotatably supported onsaid housing and spaced away from said spring and rod ends, said shaftbeing driven by said endless loop member directly through said rotatabledrive member and fixedly carrying a first link, a second link pivotallyengaging said first link and said door, whereby rotation of said shaftresults in opening and closing movement of said door, the length of saidlinks being variable for adapting said operator to either inwardly oroutwardly swinging doors.
 14. The apparatus of claim 1 including aspaced pair of rotatable members around which said endless loop memberorbits, said endless loop member being in positive driving engagementwith one said rotatable member, a housing disposed directly above saiddoor, said door drive shaft means incorporating said one rotatablemember, a shaft fixedly engaging said door on the hinge axis thereof andextending rotatably and upwardly into said housing, said shaft fixedlyengaging said one rotatable member, whereby orbiting of said endlessloop member opens and
 15. The apparatus of claim 1 in which said door isa sliding door, said endless loop member being supported in asubstantially vertical plane above said sliding door and including arotatable idler, said door drive shaft means consisting of a shaft and arotatable drive member carrying said endless loop member in cooperationwith said idler, said endless loop member directly driving saidrotatable drive member, a link fixed to said shaft and a substantiallyvertical guide track on said door slidably engaging said link, wherebyrotation of said drive member slides said door between open and closedpositions.
 16. The apparatus of claim 1 in which said door comprises apair of substantially alignable door panels hinged at remote side edgesthereof, said door operator including a housing adjacent the tops ofsaid door panels, a pair of rotatable synchronizing members on saidhousing adjacent opposite ends thereof, one said synchronizing memberbeing fixed on said door drive shaft means, an elongated loop twisted todefine substantially a ''''figure-eight'''' configuration and passingaround said rotatable synchronizing members for constraining saidmembers to rotate in synchronism and in opposite rotational directions,a first operator unit comprising said endless loop extending from saiddrive shaft means in overlapping relation with said ''''figure-eight''''loop, said motor means and return means respectively comprisingrespective powered and resilient elongate retractable members extendingfrom the reaches of said endless loop member below said''''figure-eight'''' loop.
 17. The apparatus of claim 16 including asecond door operator unit of similar kind and reversed orientationhaving a positive driving connection To the other of said synchronizingmembers and door panel.
 18. The apparatus of claim 5 including a furtherone-way valve connected in parallel with said third restrictive orificemeans to said controllable valve means and oriented to positively blockpressure fluid flow therethrough from said controllable valve means butto freely allow fluid flow therethrough toward said controllable valvemeans, whereby, when said controllable valve means is positioned toblock communication between said source and said conduit, and saidpiston is moving toward said one end of said cylinder, said furtherone-way valve maintains atmospheric pressure behind said piston.
 19. Theapparatus of claim 3 including further valve means controllable forapplying pressure fluid to said piston rod to move same in said oppositedirection for assisting said return means and including a solenoidcontrolled valve having a valve element shiftable for alternativelyallowing exhaust fluid movement out of said cylinder ahead of the pistonrod as the latter moves in said one direction for opening the door andfor applying pressure fluid to said piston to assist moving same in saidopposite direction during door closing movement.
 20. The apparatus ofclaim 19 in which said controllable valve means includes an openingsolenoid energizable for causing pressure fluid to move the piston rodin said one direction and in which said further valve means includes aclosing solenoid and a relay for controlling actuation of said closingsolenoid, said relay being connected in parallel with said openingsolenoid and adapted to energize said closing solenoid in alternativerelation to energization of said opening solenoid.
 21. The apparatus ofclaim 19 in which said further valve means includes a speed controlvalve in series with said solenoid controlled valve.
 22. The apparatusof claim 9 including pivot means for securing said opposite ends of saidreciprocable member and resilient member in said housing and a freelyrotatable idler, said endless loop member having extremities orbitallysupported by said idler and drive shaft means, said pivot means and doordrive shaft means being spaced in opposite directions longitudinally ofthe housing from said idler, said reciprocable member comprisinglongitudinally extended linear actuator means actuable for retractionand said resilient member comprising a tension spring, the firstmentioned ends of said retractable linear actuator means and springbeing fixed to opposite reaches of said endless loop means and extendingtherealong away from said drive shaft means for alternatively tensioningsaid loop means around said door drive shaft means.
 23. The apparatus ofclaim 3 including valving means connected to the one of said cylinderends approached by the piston rod moving in said one direction forcontrolling fluid flow to and from said one chamber means, a valve unitat the other end of said cylinder, and means defining a flow pathbetween said valving means and said valve unit (1) for traveling fluidto said one cylinder end to facilitate movement of said piston awaytherefrom in response to urging of said return means and (2) foralternatively traveling fluid to said valve unit at said other cylinderend during piston movement away from said other cylinder end.
 24. Theapparatus of claim 3 including valving means connected to the one ofsaid cylinder ends approached by the piston rod moving in said onedirection for controlling fluid flow to and from the chamber means atsaid one cylinder end, a valve unit at the other end of said cylinder,and means defining a flow path between said valving means and said valveunit (1) for traveling fluid to said one cylinder end to facilitatemovement of said piston away therefrom in response to urging of saidreturn means and (2) for alternatively traveling fluid to said valveunit at said other cylinder end during piston movement away from saidother cylinder end.
 25. In a door operator for a dOor movable between anopened position and a closed position, the combination comprising:endless loop means movable in opposite directions for opening andclosing said door; motor means coupled to said endless loop means andactuable for moving said endless loop means in one direction, said motormeans including a pressure fluid cylinder having a retractable pistonrod connected to said endless loop member for moving said door, a pistonon said piston rod and responsive to pressure on one side thereof formoving said piston rod in one direction, oppositely directed cam meanson said piston rod and chamber means at opposite ends of said cylindergradually blockable by respective cam means for gradually initiallydecelerating the piston rod before nearing the ends of its stroke, andvalve means controllable for applying pressure fluid to said piston rodto move same in said one direction; return means coupled to said endlessloop means and responsive to disabling of said motor means for movingsaid endless loop means in the opposite direction; whereby said motormeans and return means act through said endless loop means to move saiddoor between open and closed positions.
 26. In a door operator for adoor movable between an opened position and a closed position, thecombination comprising: endless loop means movable in oppositedirections for opening and closing said door; motor means coupled tosaid endless loop means and actuable for moving said endless loop meansin one direction; return means coupled to said endless loop means andresponsive to disabling of said motor means for moving said endless loopmeans in the opposite direction; electrically energizable means foractuating said motor means, control circuit means responsive toactuation of an actuating switch for energizing said electricallyenergizable means and for maintaining said energization for apredetermined delay time following the deactuation of said actuatingswitch, switch means responsive to actuation of a safety switch forcausing said control circuit means to hold said door open in response toprior actuation of said actuating switch occurring within said delaytime but for preventing opening of said door in response to a subsequentactuation of said actuating switch; whereby said motor means and returnmeans act through said endless loop means to move said door betwen openand closed positions.